High rates of degenerative changes in the lower spine in Calcium Pyrophosphate Deposition Disease compared to degenerative disc disease

Objective To assess the effect of calcium pyrophosphate crystal deposition disease (CPPD, chondrocalcinosis) on the axial skeleton and compare it with degenerative disc disease (DDD). Methods Conventional radiographs (CR) and Magnetic Resonance Imaging (MRI) of patients with CPPD or DDD were retrospectively assessed by two independent readers for vacuum phenomena, disc calcification, endplate erosion, osteophytes, disc height changes and spondylolisthesis. Available follow-up CR were assessed. Results CR from 140 CPPD (1.171 discovertebral units, DVU) and 99 DDD (803 DVU) were evaluated (mean age 74.4±9.9 vs. 71±6.2, 20% vs. 20.2% males, respectively). Disc calcification, osteophytes and erosions were noted significantly more frequently in CPPD vs. DDD (16.5% vs 5.2%, 73.5% vs 59.8% and 13.6% vs 3.2%, respectively, all p≤0.002). Follow-up CR from 29 CPPD and 46 DDD patients were available. Significant progression of endplate erosions and osteophytes was seen (p≤0.02) in both groups. CR follow-up in the CPPD group was compared to DDD (median (IQR) 1.9 (2.4) vs 3.0 (3.1) years, P=0.03, respectively), shorter, but radiographic thoracic erosive changes were more frequent in CPPD vs. DDD for (6.8% vs. 0.6%, P=0.02) and lumbar disc calcification (5.8% vs. 0.6%, P=0.01). Conclusion CPPD is associated with more severe and progressive structural changes in the lower spine compared to DDD. Differentiating CPPD from DDD has clinical implications, influencing both appropriate management strategies and clinical course estimation.